This invention relates in general to sealing arrangements for a bearing and shaft combination and, more particularly, to dynamoelectric machines, e.g., electric motors having bearing sealing arrangements.
In many applications of electric motors, generators, or alternators the environment is laden with dust, dirt, powder from material processing, moisture or vapors of various fluids, and mixtures of these and other contaminants which if not excluded reduce the performance and operating life of a bearing. The entrainment of these contaminants in the greases and oils used to lubricate bearings causes wear of the bearing materials by abrasion and corrosion, loss of lubricant by displacing or syphoning the lubricant from the reservoirs, and destruction of the lubricating properties of the greases and oils through dilution, thickening, or chemical attack.
Typical electric motor applications where severe environments are found include, for example, motors and generators used in railway cars, dairies, grain and feed mills, chemical processing plants, chickenhouses, air conditioning systems, construction equipment, and commercial and domestic appliances.
In the past, flexible seals of rubber or similar material have been used; however, these flexible seals have had certain shortcomings that have resulted in excessive wear and premature failure, or failure to be adaptable to excessive shaft misalignment and thus permitting leakage of the lubricant. To overcome these shortcomings labyrinth type seals which normally rquire a metal casing to retain their form and shape (which in turn increases the cost of the seal) have been used. Labyrinth seals of this type are shown, for example, in FIG. 6 of Scott's U.S. Pat. No. 3,794,392; and in FIG. 3 of Lower's U.S. Pat. No. 3,499,654. Face type seals have also been used to seal or prevent the leakage of a fluid or gas around a rotatable member like a motor shaft. Face type seals usually include a spring, bellows, and sealing ring. In order to work properly for any period of time, face type seals need to be supplied with some kind of lubrication at the sealing surfaces. The fluid being contained often provides this lubrication. Without lubrication a face type seal will fail rapidly because of seal surface wear. One example of a carbon ring having a sealing face is shown in FIG. 1 of Place's U.S. Pat. No. 3,788,650.
There is a definite advantage in forming a resilient seal that does not require a metal casing and that does not require the addition of lubricant to the fluids being contained thereby. Solutions of the above problems will be discussed in more detail hereinafter and it will be seen that the resolution of these and other problems would be particularly desirable.
Accordingly, it is an object of the present invention to provide a sealing arrangement having a resilient seal.
Another object of the invention is to provide an improved dynamoelectric machine having a bearing sealing arrangement wherein a seal is essentially self-lubricating and of long life.
Yet another object of the invention is to provide a bearing sealing arrangement wherein a seal is of a sinuous shape so that the seal may deflect under pressure and conform to variations in shaft alignment, and so that such pressure does not materially increase the engagement pressure on the contact surfaces of the seal.